Overview
11 DESCRIPTION Avapritinib is a kinase inhibitor with the chemical name ( S )-1-(4-fluorophenyl)-1-(2-(4-(6-(1-methyl-1 H -pyrazol-4-yl)pyrrolo[2,1- f ][1,2,4]triazin-4-yl)piperazin-yl)pyrimidin-5-yl)ethan-1-amine. The molecular formula is C 26 H 27 FN 10 , and the molecular weight is 498.57 g/mol. Avapritinib has the following chemical structure: The solubility of avapritinib in 0.1N HCl (pH 1.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Avapritinib is a tyrosine kinase inhibitor that targets KIT D816V, PDGFRA and PDGFRA D842 mutants as well as multiple KIT exon 11, 11/17 and 17 mutants with half maximal inhibitory concentrations (IC 50s ) less than 25 nM in biochemical assays. Certain mutations in PDGFRA and KIT can result in the autophosphorylation and constitutive activation of these receptors which can contribute to tumor and mast cell proliferation. Other potential targets for avapritinib include wild type KIT, PDGFRB, and CSFR1. In cellular assays, avapritinib inhibited the autophosphorylation of KIT D816V with an IC 50 of 4 nM, approximately 48-fold lower concentration than wild-type KIT.
Indications
- 1 INDICATIONS AND USAGE AYVAKIT is a kinase inhibitor indicated for: Gastrointestinal Stromal Tumor (GIST) the treatment of adults with unresectable or metastatic GIST harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations. ( 1.1 , 2.2 ) Advanced Systemic Mastocytosis (AdvSM) the treatment of adult patients with AdvSM. AdvSM includes patients with aggressive systemic mastocytosis (ASM), systemic mastocytosis with an associated hematological neoplasm (SM-AHN), and mast cell leukemia (MCL). ( 1.
Common Doses
- 300 mg
- 200 mg
- 25 mg
- 100 mg
Dosage
2 DOSAGE AND ADMINISTRATION GIST: Select patients for treatment with AYVAKIT based on the presence of a PDGFRA exon 18 mutation. ( 2.2 ) GIST: The recommended dosage is 300 mg orally once daily. ( 2.2 ) AdvSM: The recommended dosage is 200 mg orally once daily. ( 2.3 ) ISM: The recommended dosage is 25 mg orally once daily. ( 2.4 ) Patients with severe hepatic impairment (Child-Pugh Class C): reduce dose of AYVAKIT. ( 2.7 ) 2.1 Recommended Administration Administer AYVAKIT orally on an empty stomach, at least 1 hour before or 2 hours after a meal [see Clinical Pharmacology (12.3) ] .
Contraindications
- 4 CONTRAINDICATIONS None. None. ( 4 )
Side Effects
- 6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Intracranial hemorrhage [see Warnings and Precautions (5.1) ] Cognitive effects [see Warnings and Precautions (5.2) ] Photosensitivity [see Warnings and Precautions (5.3) ] The most common adverse reactions are: GIST (≥20% incidence): edema, nausea, fatigue/asthenia, cognitive impairment, vomiting, decreased appetite, diarrhea, increased lacrimation, abdominal pain, constipation, rash, dizziness, and hair color changes. ( 6.
Interactions
- 7 DRUG INTERACTIONS Strong and Moderate CYP3A Inhibitors : Avoid coadministration of AYVAKIT with strong and moderate CYP3A inhibitors. If coadministration of AYVAKIT with a moderate inhibitor cannot be avoided, reduce dose of AYVAKIT in patients with GIST or AdvSM. ( 2.6 , 7.1 ) Strong and Moderate CYP3A Inducers : Avoid coadministration of AYVAKIT with strong and moderate CYP3A inducers. ( 7.1 ) Hormonal contraceptives containing ethinyl estradiol : See full prescribing information for dose-specific recommendations for concomitant use ( 7.2 ) 7.